1. Field of the Invention
The present invention relates generally to an overhead projection apparatus, and more particularly to an apparatus for use in projecting a picture image onto a remote surface.
2. Description of the Prior Art
Photographic transparencies, that is, mounted slides and/or unmounted negatives, are commonly stored in clear vinyl pages. Photographic transparencies may be viewed at actual size with backlighting and may be further viewed under limited enlargement with the aid of a magnifying lens. If greater magnification is desired, or if it is desirable to project a picture image of photographic transparencies on a remote surface, a device, such as a slide viewer or projector, may be employed. This requires the photographic transparencies to be removed from the clear vinyl pages and loaded in the device or in a magazine suitable for use with the device.
An apparatus which would permit an enlargement of photographic transparencies to be easily viewed separately and independently of one another, and without removing the photographic transparencies from the clear vinyl storage page in which the photographic transparencies are stored, would offer convenience as well as reduction in the risk of damaging the photographic transparencies. Devices for enlarging photographic transparencies are well known in the prior art of record. For example, a photographic enlarger is disclosed in U.S. Pat. No. 4,129,372, issued Dec. 12, 1978 to Michael Allgeier. The photographic enlarger includes a housing having a lamp therein which directs light towards a light mixing system. A condensing lens directs light from the light mixing system towards a film slide and further towards a focusing lens located at a forwardmost end of an adjustable bellows. This enlarger is limited in its application to one photographic transparency at a time, and therefore still requires the removal of each photographic transparency to be viewed from the clear vinyl storage page in which the photographic transparencies are stored.
A visual teaching system is disclosed in U.S. Pat. No. 3,253,358, issued May 31, 1966 to John S. Wright, wherein a series of bound transparencies may be viewed individually on an overhead projector. Another patent to John S. Wright, namely, U.S. Pat. No. 3,661,449, issued May 9, 1972, discloses an overhead projector shutter assembly having a frame defining a window and a number of slides movably mounted in the frame to mask the window. The slides are selectively movable to mask and unmask selective portions of the window, or the entire window, to project selective portions of a transparency. Neither the teaching system nor the shutter assembly, as disclosed by Wright above, are applicable in viewing separate photographic transparencies without removing the photographic transparencies from the clear vinyl storage page in which the photographic transparencies are stored.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. More particularly, none of the aforementioned patents is seen to describe an apparatus for producing a picture image of separate and independent photographic transparencies on a remote surface without having to remove the photographic transparencies from a clear vinyl storage page.